<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        
        function Teacher(name, age, id) {
            this.name = name;
            this.age = age;
            this.id = id;
        }
        // Teacher.prototype.showID = function() {
        //     alert(this.id);
        // }
        // Teacher.prototype.showName = function() {
        //     alert(this.name);
        // }
        // Teacher.prototype.showAge = function() {
        //     alert(this.age);
        // }

        Teacher.prototype = {
            constructor: Teacher,
            showId: function() {
                alert(this.id);
            },
            showName: function() {
                alert(this.name);
            },
            showAge: function() {
                alert(this.age);
            }
        }
        console.dir(Teacher);

        var afei = new Teacher('afei', 66, 111);

    </script>
</body>
</html>